Expression of the le Mutation in Young Ovaries of Pisum sativum and Its Effect on Fruit Development

• Published in: Plant physiology (Bethesda) 1993-03, Vol.101 (3), p.759-764
• Main Authors: Cristina M. Santes, Hedden, Peter, Valerie M. Sponsel, Reid, James B., José L. García-Martínez
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Development and Growth Regulation; Fructification and ripening; Fruits; Fundamental and applied biological sciences. Psychology; Gibberellins; Greenhouses; Ovaries; Ovules; Peas; Pisum sativum; Plant growth; Plant physiology and development; Plants; Seed pods; Seeds; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.101.3.759

The effect of the le mutation on the growth and gibberellin (GA) content of developing fruits was investigated using the near-isogenic lines of Pisum sativum L. $205^{+}$ (LeLe) and $205^{-}$ (lele). Although stem elongation is known to be reduced in $205^{-}$ plants by approximately 65%, the growth of pods and seeds was unaffected by the le mutation. $\text{GA}_{1}$, GA3, and $\text{GA}_{20}$ stimulated parthenocarpic development of unpollinated ovaries on both $205^{+}$ and $205^{-}$ plants. $\text{GA}_{20}$ was less active on $205^{-}$ ovaries than on $205^{+}$, whereas $\text{GA}_{1}$ had similar, high activity in both lines. The activity of GA3 was even higher than that of $\text{GA}_{1}$ in both lines. Decapitation of $205^{+}$ plants induced parthenocarpic development of unpollinated ovaries, but this treatment was much less effective on $205^{-}$ plants. The contents of $\text{GA}_{1}$ and $\text{GA}_{8}$ in entire ovaries 6 d after anthesis, as well as in the pod and fertilized ovules, were substantially lower in $205^{-}$ than in $205^{+}$ plants, whereas the reverse was true for the levels of $\text{GA}_{20}$ and $\text{GA}_{29}$. These results suggest that 3β-hydroxylation of $\text{GA}_{20}$ to $\text{GA}_{1}$ is reduced in ovaries as well as in vegetative tissues. Thus, the le mutation appears to be expressed in young reproductive organs of the $205^{-}$ line, even though it does not affect the fruit phenotype. Because the content of GA3 in the ovary was similar in the two lines, one explanation for the normal fruit size in the $205^{-}$ line is that GA3 is the native regulator of pod growth. Alternatively, sufficient $\text{GA}_{1}$ may still be produced in $205^{-}$ fruits to maintain normal pod growth.